Strange intake noise?

[Captain Obvious]

Awesome! You guys beat me to it! Glad you figured it out and got the idle down to where it belongs.

11 minutes ago, chaseincats said:

 These blockoff plates really should come with instructions to give the purchaser a heads up that needs to be done.

I think that had been suggested before too. Guess it never happened.  

[Zed Head]

24 minutes ago, chaseincats said:

What was most likely happening is the intake noise was the sound of air whistling through that passageway in the throttlebody and then echoing down the intake piping.

Multi-quote doesn't work across two pages weird.  Had to stick an image in there instead.

You had a block-off plate on the other two TB's?  Just wondering....

 

[chaseincats]

8 minutes ago, Zed Head said:

Multi-quote doesn't work across two pages weird.  Had to stick an image in there instead.

You had a block-off plate on the other two TB's?  Just wondering....

 

No but when we held the other on the manifold we just covered the bottom with our palm essentially doing the same thing as the plate...

[Zed Head]

So you destroyed two other BCDD's/TB's?  Not good.

Anyway, at least one problem down.  Good luck.

[chaseincats]

17 minutes ago, Zed Head said:

So you destroyed two other BCDD's/TB's?  Not good.

Anyway, at least one problem down.  Good luck.

If leaving the bcdd at the junkyard means the throttlebody is destroyed then i guess so

[chaseincats]

So we got it running without a hiss and it idles great but when we hit the gas it heavily stumbles and front fires.

We have an air fuel gauge on it and it goes off the charts lean the second you hit the pedal but idles in the mid 13s on the gauge.  I tested the TPS by unplugging it and the car runs leaner with it unplugged and richer replugged telling me it’s working.

The coolant temp sensor is new as are the connectors for it.  We put a fuel pressure gauge on it and it’s sitting more-or-less where it should be (36-40psi) idling and with the pedal pressed.  Even if that isn’t 100% correct it should be running out of gas as-is.  One thing I noticed that’s strange is the car won’t even start with the coolant temp sensor unplugged (before we sealed vacuum leaks it started right up).  Not sure if that helps or not though.

I made a video which might help: https://youtu.be/bq_ppptWZxI

Edited August 20, 2022 by chaseincats

[Zed Head]

Are you sure the AFM is plugged in?  You can check at the ECU connector.  That's actually the best place anyway.

I'd say try the fuel tweaker but if it won't rev with no load then it's probably not seeing the AFM signal.  Also, you might pop the black cover on the AFM and be sure the vane is moving when the throttle opens.  Quick and easy.  If the vane doesn't move the ECU doesn't add fuel.

Here's the tweaker for future ref -

http://www.atlanticz.ca/zclub/techtips/tempsensorpot/index.html

[chaseincats]

33 minutes ago, Zed Head said:

Are you sure the AFM is plugged in?  You can check at the ECU connector.  That's actually the best place anyway.

I'd say try the fuel tweaker but if it won't rev with no load then it's probably not seeing the AFM signal.  Also, you might pop the black cover on the AFM and be sure the vane is moving when the throttle opens.  Quick and easy.  If the vane doesn't move the ECU doesn't add fuel.

Here's the tweaker for future ref -

http://www.atlanticz.ca/zclub/techtips/tempsensorpot/index.html

We tried that one already and all the ECU connector tests in the fuel injection bible but everything checks out correctly.

We know the AFM is working because if we turn the large gear inside the afm the air fuel gauge’s numbers change, so it is working. We did take the ecu out and it does have some brown dried liquid on it if that means anything.

here are some pictures if it helps.  I also attached an image of a sensor not on my 78  either just in case that has anything to do with it.  It sits on the thermostat mount below the fuel rail.

[Zed Head]

Open the AFM vane before you open the throttle it should rev because of the extra fuel if it's a fuel problem.  You didn't say that the vane actually moves with air flow.  Maybe it moves a little and stops.

Might be that the AMF is not right now.  Work and work right are not the same thing.

14 minutes ago, chaseincats said:

We know the AFM is working because if we turn the large gear inside the afm the air fuel gauge’s numbers change, so it is working. We did take the ecu out and it does have some brown dried liquid on it if that means anything.

 

[chaseincats]

On 8/20/2022 at 7:43 PM, Zed Head said:

Open the AFM vane before you open the throttle it should rev because of the extra fuel if it's a fuel problem.  You didn't say that the vane actually moves with air flow.  Maybe it moves a little and stops.

Might be that the AMF is not right now.  Work and work right are not the same thing.

 

We noticed the water temp switch was unplugged, and when plugged in the car ran way better.  He is not using the transistor ignition module, so why would the car run differently with this hooked up as I thought that was only tied to the stock ignition system.  Any ideas?

Edited August 23, 2022 by chaseincats

[Racer X]

3 hours ago, chaseincats said:

We noticed the water temp switch was unplugged, and when plugged in the car ran way better.  He is not using the transistor ignition module, so why would the car run differently with this hooked up as I thought that was only tied to the stock ignition system.  Any ideas?

The ignition doesn't need to know the temperature, the fuel injection system does. Cold engine, enrich the mixture. Warm engine, lean it out.

[Captain Obvious]

11 hours ago, chaseincats said:

We noticed the water temp switch was unplugged, and when plugged in the car ran way better.  Any ideas?

I did not pour over the 75 wiring diagram, but for other years, a temperature switch controlled things like ignition timing and EGR engagement. I understand that you're not running the original ignition module, but maybe somehow you're getting EGR pumped into the intake manifold when you shouldn't be?

Just tossing out ideas.